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which commences about five miles below Wisbeach, and terminates after a length of five miles in the great estuary of the Wash. The benefits of this improvement have been very great; the low water mark has been lowered 10 ft. 6 in., and a district of more than 100,000 acres, formerly a stagnant marsh, has been brought into cultivation.

72. Closely allied with the drainage of low lands, are the operations by which their boundaries are extended, and large districts actually reclaimed from the action of the sea. This is effected by judiciously controlling the deposit of the alluvial materials which are washed down with the drainage waters and thrown back by the tide. This requires the formation of embankments or opposing barriers, by which the removal of those materials is prevented. A similar artificial mode of depositing the solid matters contained in the water is practised in the interior districts by surrounding them with embankments, and admitting and discharging the water by means of sluices and canals. This method has for many years been adopted with great success in the rivers Trent, Ouse, and Humber.

73. Districts lying below the level of the adjacent river, or so little above it that drains of adequate capacity must have their beds below the water-line, necessarily require artificial means of discharging the drainage waters into the receiving channel or river. In the low lands of Holland this is commonly the case, and accordingly we find the Dutch were early adopters of contrivances for this purpose. Fig. 21 shows the relative conditions of the drain and of the river into which its contents are required to be discharged. A represents the general level of the district; B, that of the water in the drain to be discharged; c, the top of embankment;

A

B

Fig. 21.

D

and D, the high water level outside. To transfer the contents of the drain в into the main channel D, it is evidently only necessary to erect upon the embankment, pumps, buckets, or scoops, which shall bring the water up on the one side and discharge it on the other. Among the earlier machines employed by the Dutch were scoop wheels, which they worked by means of windmills, and continued to use for many ages. A new form of scoop or alternating trough has been designed by Mr. W. Fairbairn, and adapted to be worked by the single acting Cornish engine.

74. Fig. 22 will serve to give a general idea of this contrivance. A is the bail scoop, turning on a centre at B, fixed on the embankment c. The other end of the scoop is connected at D by a connecting rod with the end E, of the engine-beam F, of which & is the centre, and erected upon suitable foundations, H. I represents the level of water in the river, and J, the drain from which the water is to be discharged. The action of the apparatus will be evident from inspection of the figure. The engine employed is of the reciprocating kind, and by raising a weight suspended at the other end of the

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engine-beam F, the bailing scoop A descends, and becomes filled with the drainage water through the opening valves at K. The weight having been raised to the height of the stroke, descends by its own gravity, and raising the end, D, of the scoop discharges its contents into the river at I. This apparatus is well adapted to be worked by the single acting Cornish engine, and while the length of stroke in the cylinder always remains the same, the dip is regulated as required by shifting the connecting rod at the ends D and E. The scoop is made of iron boiler plates, and is 25 ft. long and 30 ft. wide, with two partitions across it to strengthen the sides and afford bearings for the valves at к. The machine is adapted to raise 17 tons of water at each stroke, and, with an engine of 60-horse power, will do a duty equal to 3 lbs. of coal, per horse power, per hour.

K.

75. The greatest improvement, however, effected in mechanical draining is by the employment of the steam engine for this purpose. In the year 1820, Rennie applied one of Watt's engines to the working of a large scoop wheel for draining Bottisham Fen, near Ely Since that time large districts have been efficiently drained by steam power; and of them we may enumerate the following:

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76. If the drainage from the high lands be discharged through catch-water drains, that from the low levels will consist of the rain water only, and as this, in the fen districts on the eastern side of England, seldom exceeds the average of 26 in. in depth per annum, of which a large quantity is carried off by evaporations and absorption, 2 in. in depth or 1 cubic ft. of water on every square yard of surface is the ordinary maximum quantity to be lifted per month. Adopting the admitted standard of horse power, viz., 33,000 lbs., raised one foot per minute, and the weight of a cubic foot of water

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to equal 62 lb., or 10 lb. per gallon, a horse's power will raise 330 gallons, or 52.8 cubic ft. of water 10 ft. high per minute. The total quantity to be raised per acre per month, viz. 7260 cubic ft., may thus be raised a height of 10 ft., and discharged in about 2 hours and 10 minutes. Upon this calculation, which Mr. Glyn (a high and practical authority in these matters) has found to be supported in practice, it appears that a steam engine of 10-horse power will raise and throw off the drainage water due to a district of 1000 acres of fens, in each month, in 232 hours, or less than 20 days, working 12 hours a day. The scoop-wheels used for raising the water resemble an undershot water-wheel, but, instead of being moved by the force of the water, they are adapted for forcing the water upward, deriving their motion from the steam engine. The float boards or ladle boards are of wood, and fitted to work within a track or trough of masonry: they are usually about 5 ft. long, that is, they are immersed in the water to that extent, the width or horizontal dimension of them being varied, according to the power of the engine and the head of water to be provided for, from 20 in. to 5 ft. The lower end of the wheel track communicates with the main drain, and the higher end with the river, the water of which is excluded by a pair of doors, pointing like the gates of a canal lock, and closed when the engine ceases to work. The wheels are of cast iron, and fitted in parts. The float boards are attached to the wheel by oak starts, stepped into sockets cast in the periphery of the wheel for that purpose. The wheel is fitted with cast-iron toothed segments, working into a pinion upon the crank shaft of the engine. If the level of water in the delivering drain and in the river does not vary much, one speed for the wheel is sufficient; but if the

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